Structural highlights
Function
[BAMA_ECOLI] Part of the outer membrane protein assembly complex, which is involved in assembly and insertion of beta-barrel proteins into the outer membrane. Constitutes, with BamD, the core component of the assembly machinery.[1] [2] [3] [4] [5]
Publication Abstract from PubMed
The beta-Barrel Assembly Machinery (BAM) mediates folding and insertion of beta-barrel outer membrane proteins (OMPs) into the outer membrane of Gram-negative bacteria. BAM is a five protein complex consisting of the beta-barrel OMP BamA and lipoproteins BamB, C, D, and E. High resolution structures of all the individual BAM subunits and a BamD-BamC complex have been determined. However, the overall complex architecture remains elusive. BamA is the central component of BAM and consists of a membrane embedded beta-barrel and a periplasmic domain with five Polypeptide Translocation Associated (POTRA) motifs thought to interact with the accessory lipoproteins. Here we report the crystal structure of a fusion between BamB and a POTRA3-5 fragment of BamA. Extended loops 13 and 17 protruding from one end of the BamB beta-propeller contact the face of the POTRA3 beta-sheet in BamA. The interface is stabilized by several hydrophobic contacts, a network of hydrogen bonds, and a cation-pi interaction between BamA Y255 and BamB R195. Disruption of BamA:BamB binding by BamA Y255A and probing of the interface by disulfide bond crosslinking validate the physiological relevance of the observed interface. Furthermore, the structure is consistent with previously published mutagenesis studies. The periplasmic five-POTRA domain of BamA is flexible in solution due to hinge motions in the POTRA2-3 linker. Modeling BamB in complex with full-length BamA shows BamB binding at the POTRA2-3 hinge suggesting a role in modulation of BamA flexibility and the conformational changes associated with OMP folding and insertion.
Crystal Structure of BamB Bound to a Periplasmic Domain Fragment of BamA, the Central Component of the beta-Barrel Assembly Machine.,Jansen KB, Baker SL, Sousa MC J Biol Chem. 2014 Dec 2. pii: jbc.M114.584524. PMID:25468906[6]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
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- ↑ Werner J, Misra R. YaeT (Omp85) affects the assembly of lipid-dependent and lipid-independent outer membrane proteins of Escherichia coli. Mol Microbiol. 2005 Sep;57(5):1450-9. PMID:16102012 doi:http://dx.doi.org/MMI4775
- ↑ Malinverni JC, Werner J, Kim S, Sklar JG, Kahne D, Misra R, Silhavy TJ. YfiO stabilizes the YaeT complex and is essential for outer membrane protein assembly in Escherichia coli. Mol Microbiol. 2006 Jul;61(1):151-64. PMID:16824102 doi:http://dx.doi.org/10.1111/j.1365-2958.2006.05211.x
- ↑ Hagan CL, Kim S, Kahne D. Reconstitution of outer membrane protein assembly from purified components. Science. 2010 May 14;328(5980):890-2. doi: 10.1126/science.1188919. Epub 2010 Apr, 8. PMID:20378773 doi:10.1126/science.1188919
- ↑ Hagan CL, Kahne D. The reconstituted Escherichia coli Bam complex catalyzes multiple rounds of beta-barrel assembly. Biochemistry. 2011 Sep 6;50(35):7444-6. doi: 10.1021/bi2010784. Epub 2011 Aug 11. PMID:21823654 doi:10.1021/bi2010784
- ↑ Jansen KB, Baker SL, Sousa MC. Crystal Structure of BamB Bound to a Periplasmic Domain Fragment of BamA, the Central Component of the beta-Barrel Assembly Machine. J Biol Chem. 2014 Dec 2. pii: jbc.M114.584524. PMID:25468906 doi:http://dx.doi.org/10.1074/jbc.M114.584524
